Normally one of Labour's strongest Commons performers, Ed Balls visibly struggled yesterday as he responded to George Osborne's Autumn Statement. In an interview on the Today programme this morning, the shadow chancellor sought to explain why. As I suggested yesterday, it was the news that borrowing is set to fall, rather than rise, this year (owing to Osborne's manipulation of the figures) that wrongfooted Balls. Here's what he told Sarah Montague.

What happens in the House of Commons when you are responding to that statement is you have none of the figures, none of the documentation, and you have to listen to the chancellor. The outside forecasters were all expecting a rise in borrowing this year, because it has risen for the first seven months ... it was impossible to work out in that first minute or two what was going on.

The reason is because the Chancellor decided to slip the money for the 4G mobile spectrum into this financial year but he did not even say that in the House of Commons.

Asked whether he did his job "well enough yesterday", Balls made reference to his stammer.

Everybody knows with me that I have a stammer and sometimes my stammer gets the better of me in the first minute or two when I speak, especially when I have got the Prime Minister, the Chancellor and 300 Conservative MPs yelling at me at the top of their voices. But frankly, that is just who I am, and I don’t mind that. What I want to do is win the arguments about what is right for Britain, for jobs, for our economy, for our deficit, and for lower and middle income families in our country. And that is more important to me Sarah than the first two minutes of an exchange with people braying over the dispatch box and I don’t apologise for one second. I’ll keep making the arguments.

But in his own interview on Today, Osborne declared: "It's got nothing to do with the fact that he [Balls] has got a stammer, it is because he was the chief economic adviser when it all went wrong, and he never acknowledges that." Ever mischievous, the Chancellor also praised David Miliband (one of those previously touted as shadow chancellor), who he claimed had acknowledged Labour's mistakes.

Privately, Labour figures concede that Osborne won the political battle yesterday, but with no end to the grim economic news in sight, the smart money is still on Balls to triumph.